code: def dynamic_import_lm(module, backend):
      """Import LM class dynamically.
  
      Args:
          module (str): module_name:class_name or alias in `predefined_lms`
          backend (str): NN backend. e.g., pytorch, chainer
  
      Returns:
          type: LM class
  
      """
      model_class = dynamic_import(
          module, predefined_lms.get(backend, dict())
      )
      assert issubclass(
          model_class, LMInterface
      ), f"{module} does not implement LMInterface"
      return model_class
  
file_path: espnet/espnet/nets/lm_interface.py
imports: import argparse
  from espnet.nets.scorer_interface import ScorerInterface
  from espnet.utils.dynamic_import import dynamic_import
  from espnet.utils.fill_missing_args import fill_missing_args
label_desc: Use image node_id 1 for calling a global function with example usage: dynamic_import_lm(module, backend) and returns: model_class